So I am trying to develop using UI5 and I can not seem to open Eclipse. Every time I open the program it says the following: "The Application 'eclipse' can't be opened". Does anyone have a solution. I downloaded a version that already has an IDE built in. Is that a possible issue?

I had no problems installing the Keppler version : look at
http://www.eclipse.org/downloads/
-> go to Kepler
Look for Eclipse IDE for Java EE Developers (MAC 64 Bit), this will
download the file eclipse-jee-kepler-SR2-macosx-cocoa-x86_64.tar.gz !
Just open (unpack) it, it will create an entry: Eclipse.app.

Afterwards, when done, open Eclipse and install the
"SAP UI5 – Development Toolkit" in Eclipse through:
Help/Install new software/ open site -> https://tools/hana.ondemand.com/kepler

Best Luck, Markus